1. Field of the Invention
The present invention relates to a memory structure and an array thereof, and more particularly to a non-volatile memory structure and an array thereof.
2. Description of Related Art
Among various non-volatile memories, an electrically erasable programmable read only memory (EEPROM) permits multiple data input, retrieval and erasure. Furthermore, input data can still be retained after a power supply to a device is removed. Therefore, the EEPROM has become one of the most popular memory devices adopted in personal computers and electronic equipment.
A typical EEPROM has a floating gate and a control gate which are both fabricated by doped polysilicon. As the memory is programmed, electrons injected into the floating gate are uniformly distributed in a polysilicon floating gate layer.
In addition, another conventional EEPROM employs a charge trapping layer as a replacement of the polysilicon floating gate, and the charge trapping layer is, for example, made of silicon nitride. Usually, a silicon oxide layer is disposed at respective sides of the silicon nitride charge trapping layer, so as to form a stacked gate structure including a silicon oxide/silicon nitride/silicon oxide (ONO) composite dielectric layer.
Silicon oxide isolation patterns used for isolating doped regions or separating two adjacent word lines are disposed on a substrate surrounding a channel region of the afore-mentioned conventional memory. To be more specific, the silicon oxide isolation patterns are disposed on the substrate above the doped regions or between the two adjacent word lines. However, the aforesaid conventional memory may have unfavorable electrical performance, such as low reading current, unsatisfactory transconductance (GM), low programming speed, short data retention time, and so on.
Furthermore, fabrications of the silicon oxide isolation patterns disposed above the doped regions require complicated manufacturing methods, such as a lift-off method, and so forth. Accordingly, production efficiency and yield rate of products may be deteriorated.